1. Field of the Invention
The invention relates to a device that reduces torsional vibration due to reciprocating motion or pendulum motion of an inertial mass.
2. Description of Related Art
Examples of this kind of device are described in International Publication No. WO 2013/161058, International Publication No. WO 2013/128590, and Japanese Patent Application Publication No. 2013-44370 (JP 2013-44370 A). In these devices, inertial mass is configured as a rolling element, and this rolling element is housed in a rolling chamber formed in a rotating body. These devices are configured to reduce torsional vibration when it is generated in the rotating body, by the rotating body moving inside the rolling chamber in a reciprocating manner according to the torsional vibration. Each of these devices is arranged inside of a torque converter. With the structures described in International Publication No. WO 2013/161058 and International Publication No. WO 2013/128590 in particular, the rolling element and rolling surface are covered by a case member so that the reciprocating motion of the rolling body will not be impeded or affected by oil. A seal member is provided between this case member and the rotating body. As a result, a space formed by the case member is kept liquid-tight, and the case member and the rotating body are able to rotate relative to one another.
Also, with the structure described in International Publication No. WO 2013/128590, a torsional damper is arranged overlapping a torsional vibration reduction device in the axial direction and farther to the inside than the torsional vibration reduction device in the radial direction of the rotating body. In briefly describing the structure of the torsional damper, the case member described above is formed by a pair of plates, and these plates also serve as an input side member of the torsional damper. The rotating body becomes the output side member of the torsional damper, and this output side member is arranged between the pair of plates. Also, the plates and the rotating body are connected together, in a manner such that power is able to be transferred, via a spring. Furthermore, JP 2013-44370 A describes a torsional vibration reduction device formed with a rotating body fastened to a turbine shell of a turbine runner by a rivet.
With the structures described in International Publication No. WO 2013/161058 and International Publication No. WO 2013/128590, the space may also be sealed by welding a gap between the rotating body and the case member. However, in this case, if the material of which the rotating body is formed is different from the material of which the case member is formed, welding between these materials may be difficult.
With the structure described in JP 2013-44370 A, because the rotating body and the turbine shell are fastened together by a rivet, a rivet that is longer by an amount corresponding to the thickness of the rotating body is used. That is, the reliability of the joint of these members may decrease as the length of the rivet increases.